.gitignore: fix directory patterns for ugrep.

ugrep will only ignore directories listed in .gitignore if they are
terminated with a slash. We want git to still match symlinks, so leave
the non-terminated entries in.

.gitignore

@@ -5,6 +5,8 @@
 *.o
 masterdir*
 hostdir*
+masterdir*/
+hostdir*/
 etc/conf
 etc/conf.*
 etc/virtual